Mechanical muscle function and lean body mass during supervised strength training and testosterone therapy in aging...

To examine the effect of strength training and testosterone therapy on mechanical muscle function and lean body mass (LBM) in aging men with low-normal testosterone levels in a randomized, double-blind, placebo-controlled 24-week study.

Randomized, double-blind, placebo-controlled.

Odense, Denmark.

Men aged 60 to 78, with bioavailable testosterone levels of less than 7.3 nmol/L and a waist circumference greater than 94 cm were randomized to testosterone (50-100 mg/d, n = 22) placebo (n = 23) or strength training (n = 23) for 24 weeks. The strength training group was randomized to addition of testosterone or placebo after 12 weeks. Subjects performed supervised strength training (2-3 sets with 6- to 10-repetition maximum loads, 3 times per week).

Testosterone levels, maximal voluntary contraction and rate of force development, and LBM were obtained at 0 and at Weeks 12 and 24 of the intervention.

No changes in any variables were recorded with placebo. In the strength training group, maximal voluntary contraction increased 8% after 12 weeks (P = .005). During the following 12 weeks of strength training rate of force development increased by 10% (P = .04) and maximal voluntary contraction further increased (P < .001). Mechanical muscle function was unchanged in men receiving only testosterone for 24 weeks. LBM increased only in men receiving testosterone (P = .004).

Strength training in aging men with low-normal testosterone levels may improve mechanical muscle function, but this effect occurs without a significant increase in LBM. Clinically, only the combination of testosterone therapy and strength training resulted in an increase in mechanical muscle function and LBM.